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Installation of focal-plane scintillator

Vent focal-plane chamber

  • Open the HV Remote Control GUI and ensure that the focal-plane detectors are unbiased
  • Open the Labview gas handling system and verify that there is no gas in the CRDCs and IC. Open valves 4 (IC supply), 5 (IC bypass), 6 (IC focal-plane bypass), 20 (CRDC supply), 21 (CRDC bypass), and 22 (CRDC focal-plane bypass). The rest of the valves should be closed
  • Ensure that the manual venting valve located on the south side of the chamber is closed (see figures below) FP chamber manual venting valve FP chamber manual venting valve
  • Ensure that the FP ion gauge (I264IG) is off (see details here)
  • Open PanelMate and select S800vac file in directory \\exp\files\control\ncsdata\General\Qt\Templates. Go to page 07, and ensure that I265GV (gate valve separating FP box from rest of beam line) is closed.
  • Click on the VENT STATUS window and begin the venting procedure. The VENT VALVE I260VV window will turn red and display “OPEN”. The pressure should remain constant because the manual venting valve is still closed
  • Gently open the manual venting valve until the pressure displayed in the Pirani Gauge (see figure below) increases by ~1 torr every 15 seconds (see figures below)

FP chamber manual venting valve

  • Wait until the chamber is vented (few hours). The I261PG Pirani Gauge should read slightly above atmospheric pressure (due to the dry N2 flow pumped to the chamber). The window VENT STATUS in PanelMate should display “VENT VALVE OPEN”. The window PUMPDOWN STATUS should display “PUMPDOWN STOPPED”
  • When the chamber is fully vented, select VENT STATUS and click STOP VENTING PROCEDURE
  • Close the manual vent valve

Open focal-plane chamber

  • After venting the FP chamber, the pressure inside the chamber is slightly above atmospheric due to the dry N2 pumped. Before opening the chamber, it is recommended to vent the extra N2 by “forcing” the pressure-relief valve with e.g. a screwdriver screwdriver-flange.jpg
  • Unlock the padlock protecting the power brakers of the switch controls to open the chamber, and press the START button Padlock
  • Turn the switch to open the clamps holding the FP chamber. The weight held by the hydraulic piston will increase Switch clamps Clamps holding FP chamber Scale FP chamber
  • Turn on the switch to activate the motor opening the chamber. It takes about 10 minutes to get the chamber totally opened Motor switch to open FP chamber

Installing FP scintillator

  • The figure below shows the FP chamber open, with the “old” FP scintillator to be replaced by the new one FP chamber opened
  • Unplug the bases of the up and down phototubes. The platic tie holding the cable of the up phototube to the chamber needs to be cut UP base phototube DOWN base phototube
  • Using an allen wrench, unscrew the two bolts attaching the scintillator frame to the base of the chamber Scintillator frame
  • Climb to the chamber and pull the scintillator frame up. Once unplugged, handle it to a second person FP chamber opened FP chamber opened
  • With the help of a second person, hold the new scintillator by its frame and place it in the right spot. A second person should be ready to screw the frame to the base of the chamber
  • Connect the bases of the up and down phototubes. The later is quite difficult because one cannot see the pins
  • Using a plastic tie, attach the cable of the up phototube to the scintillator frame

Closing focal-plane chamber

  • Turn the switch to move the chamber to position “UP”, and keep it that way for about 10 minutes (the time it takes the chamber to be closed)
  • Check the display indicating the weight lift by the hydraulic system. When the chamber is close, the weight displayed will increase drastically due to the resistance experienced by the hydraulic system. At that point, stop immediately the lifting switch (otherwise, a weight-limit set point might be reached, disabling the hydraulic system)
  • Turn the knob to close the clamps
  • Inspect the clamps and chamber flange (no gaps) to ensure that the chamber is properly sealed
  • Before pumping the chamber down, make sure that the scintillator is properly connected. This can be done by biasing the detector and checking the signals, either from the scalers or with a scope. One should clearly see cosmic rays; if that is not the case, the phototubes are likely miss connected

Pumping focal-plane chamber

  • Make sure that the pressure-relief valve and the manual vent valve (see above) are closed.
  • Make sure that manual valve of the mechanical pump is opened Manual valve pump
  • Open PanelMate S800vac and go to page 07. Make sure
  • Select window PUMPDOWN STATUS and click on button START PUMPDOWN. The PUMPDOWN STATUS and VENT STATUS windows should display “PUMPDOWN IN PROGRESS”
  • Wait for some hours until vacuum is good
installation_fp_sci.1497993324.txt.gz · Last modified: 2017/06/20 17:15 by pereira